The electron donor properties of Cu+ and the ability to activate adsorbed molecules by π-back donation of d electrons of Cu+ to π* antibonding orbitals of a molecule increases in the order: CuMCM-41 < CuZSM-5 < CuBeta. It was evidenced by IR studies of CO, N2, and NO adsorption. TPD-IR experiments provided information on heterogeneity of Cu+ sites in all the zeolites studied. The experiments on the reduction (in H2) and oxidation (in air) evidenced that the ability of Cu+ to reduction and oxidation depends on zeolite structure. The ability to reduction increased in the order: CuMCM-41 < CuBeta < CuZSM-5, whereas the ability to oxidation increased in the opposite order.
- IR spectroscopy